This disclosure is generally directed to layered imaging members, photoreceptors, photoconductors, and the like. More specifically, the present disclosure is directed to multilayered drum, or flexible, belt imaging members, or devices comprised of a first layer, a supporting medium like a substrate, a photogenerating layer, and a charge transport layer, including a plurality of charge transport layers, such as a first charge transport layer and a second charge transport layer, an optional adhesive layer, an optional hole blocking or undercoat layer, and an optional overcoating layer, and wherein the supporting substrate is situated between the first layer and the photogenerating layer. More specifically, the photoconductors disclosed contain a first anticurling backside coating layer or curl deterring backside coating (ACBC) to, for example, render imaging member flatness, and which layer is in contact with and contiguous to the reverse side of the supporting substrate, that is this side of the substrate that is not in contact with the photogenerating layer, and which first layer, the ACBC of present disclosure, is comprised of a polymer and an additive of needle shaped particles such as silica, alumina, metal oxides like titanium dioxide, fluorinated polymers such as polytetrafluoroethylenes, a polyvinylfluoride, and the like.
In some instances when a flexible layered photoconductor belt is mounted over a belt support module comprising various supporting rollers and backer bars in a xerographic imaging apparatus, the anticurl or reduction in curl backside coating (ACBC), functioning under a normal machine operation condition, is repeatedly subjected to mechanical sliding contact against the apparatus backer bars and the belt support module rollers to thereby adversely impact the ACBC wear characteristics. Moreover, with a number of known prior art ACBC photoconductor layers formulated to contain non-needle like additives the mechanical interactions against the belt support module components can decrease the lifetime of the photoconductor primarily because of wear and degradation after short time periods.
In embodiments, the photoconductors disclosed include an ACBC (anticurl backside coating) layer on the reverse side of the supporting substrate of a belt photoreceptor. The ACBC layer, which can be solution coated, for example, as a self-adhesive layer on the reverse side of the substrate of the photoreceptor, may comprise a number of suitable materials such as those components that do not substantially effect surface contact friction reduction and prevents or minimizes wear/scratch problems for the photoreceptor device. In embodiments, the mechanically robust ACBC layer of the present disclosure usually will not substantially reduce the layer's thickness over extended time periods to adversely effect its anticurling ability for maintaining effective imaging member belt flatness, for example when not flat, the ACBC layer can cause undesirable upward belt curling which adversely impacts imaging member belt surface charging uniformity causing print defects which thereby prevent the imaging process from continuously allowing a satisfactory copy printout quality; moreover, ACBC wear also produces dirt and debris resulting in dusty machine operation condition. Since the ACBC layer is located on the reverse side of the photoconductor, it does not usually adversely interfere with the xerographic performance of the photoconductor, and decouples the mechanical performance from the electrical performance of the photoconductor.
Moreover, high surface contact friction of the anticurl backside coating against the machine, such as printers, subsystems can cause the development of undesirable electrostatic charge buildup. In a number of instances with devices, such as printers, the electrostatic charge builds up because of high contact friction between the anticurl backside coating and the backer bars which increases the frictional force to the point that it requires higher torque from the driving motor to pull the belt for effective cycling motion. In a full color electrophotographic apparatus, using a 10-pitch photoreceptor belt, this electrostatic charge build-up can be high due to the large number of backer bars used in the machine.
Some anticurl backside coating formulations are disclosed in U.S. Pat. Nos. 5,069,993; 5,021,309; 5,919,590; 4,654,284 and 6,528,226. However, there is a need to create an anticurl backside coating formulation that has intrinsic properties that minimize or eliminate charge accumulation in photoconductors without sacrificing other electrical properties such as low surface energy. One ACBC design can be designated as an insulating polymer coating containing additives, such as silica or TEFLON®, to reduce friction against backer plates and rollers, but these additives tend to charge up triboelectrically due to their rubbing against it resulting in electrostatic drag force that adversely affects the process speed of the photoconductor.
The anticurl backside coating layers illustrated herein, in embodiments, have excellent wear resistance, extended lifetimes, minimal charge buildup and permit the elimination or minimization of photoconductive imaging member belt ACBC scratches.
Also included within the scope of the present disclosure are methods of imaging and printing with the photoresponsive or photoconductor devices illustrated herein. These methods generally involve the formation of an electrostatic latent image on the imaging member, followed by developing the image with a toner composition comprised, for example, of thermoplastic resin, colorant, such as pigment, charge additive, and surface additive, reference U.S. Pat. Nos. 4,560,635; 4,298,697 and 4,338,390, the disclosures of which are totally incorporated herein by reference, subsequently transferring the toner image to a suitable image receiving substrate, and permanently affixing the image thereto. In those environments wherein the device is to be used in a printing mode, the imaging method involves the same operation with the exception that exposure can be accomplished with a laser device or image bar. More specifically, the flexible photoconductor belts disclosed herein can be selected for the Xerox Corporation iGEN® machines that generate with some versions over 100 copies per minute. Processes of imaging, especially xerographic imaging and printing, including digital, and/or color printing, are thus encompassed by the present disclosure. The imaging members are in embodiments sensitive in the wavelength region of, for example, from about 400 to about 900 nanometers, and in particular from about 650 to about 850 nanometers, thus diode lasers can be selected as the light source. Moreover, the imaging members of this disclosure are useful in color xerographic applications, particularly high-speed color copying and printing processes.